SU721796A1 - Recirculation measuring time-to-code converter - Google Patents

Description

The invention relates to radio electronics and can be used in radio measurement instruments for measuring time intervals, as well as in telemetry systems for analog-to-discrete conversion. A time interval meter is known that makes it possible to obtain a digital code proportional to the duration of the input interval 1. The disadvantages of such a meter include the fact that in order to obtain the result of the conversion, it is necessary to carry out additional processing of the readings of several counters. This leads to an increase in conversion time and the amount of equipment used. In this device, an increase in accuracy is achieved by increasing the number of taps from the measurement delay line. The number of taps should not exceed the allowable number of taps at which the parameters of the measuring delay line remain unchanged. This circumstance limits the accuracy of the device. The closest in technical essence is a device for discrete measurement of time intervals containing delay elements, triggers, AND, OR elements, shapers that form a closed recirculation circuit 2. The disadvantages of such a device include a small range of input measured signals, which significantly limits the scope of the device. To increase the range of measured intervals, the device needs to use a delay line with a large delay time (longer than the maximum possible measured interval), which leads to a deterioration in the range of metrological characteristics of the meter, such as accuracy and measurement time. The aim of the invention is to expand the range of measurable inter-r shafts of time while maintaining the measurement accuracy. The goal is achieved by the fact that the converter containing the pulse shaper, to the input of which the device input bus is connected, a trigger, the first input of which is connected to,, ;; X; lCOL1ffp vSHpovateJiig pulses, -laTi-jpa delay element, element OR; two AND elements, the output of the first of which is connected through the first delay element to the first input; the OR element, the output of the second support element is connected to the first input of the STCpoo I element, additionally to 3.3; yk element is NOT. two jumpers OR minority and high order bits of the reversible counter, with the input of the pulse former connected directly to the first input of the first AND element and the control inputs of the old W .4X and -1L, 1% of the reversing C & and the third delay element with the second input is an OR tape, the output of which is connected to the second input of the first element V Р whose output is connected to;., - ;: vsoMy THE INPUT first year completes the first element -OR, the output of the first: - ,, aaa tape of the delay is connected second, with the trigger house, the output of which is connected to the first input of the second additional element OR, the output ;; is costly connected directly to the input of the second delay element and through the fourth delay element to the second input of the second element AND, the exit of which is connected to the second input of the second additional OR element and to the counting to the input of the lower bits of the reversible counter, the output of which through the first additional element OR is connected with the counting input of the higher bits of the reversible counter.

In Fig. 1, avlena is a structural diagram of the proposed converter; FIG. 2 shows timing diagrams explaining his work.

The recirculation time transmitter - the code contains pulse shaper 1, HE.2 element, trigger 3, OR elements 4-6, delay elements 7-10, AND elements 11, 12, low bits of the reversible counter 13, high bits of the reversible counter 14,

The device works as follows.

The measured time interval t (Fig. 2.a) arrives at the input of the element HE 2 y at the input of the element 11. With the output element NO 2 (Fig. 2.6), the inverted signal is delayed by the delay term 7 at time t and through Element OR 5 enters the second element AND 11. At the output of element 11, an impulse signal of duration f is formed which through the element OR b enters the counting input of the higher bits of the reverse, j; BHOro of the counter 14. Senior and young: the bits of the reversible counter k; 4 ci-.c. ssiT In mode, summed i ;; .. When the counter counters 13 and 14 are set to subtract mode. The pulse from the output of the element 11, delayed by the element of delay 10 for the time T, passes through the element OR 5 to the second input of the element 11, Then the process of circulation of the pulse of duration t and with the period of circulation T will occur as described above

the first circulation cycle (Fig. 2.b). Circulation breakdown will occur at the moment of the end of the measured interval t. The number of circulation cycles is recorded by the higher bits of the reversible counter 14. At the end of measuring S of the interval 1 in the counter. 14, a code proportional to the duration of the measured signal T vt N-T will be recorded.

The measurement result is greater than the actual interval by the value of At-,

therefore, to clarify it not. It is taken from the N code of the higher bits of the reversible counter 14 to subtract a code proportional to the time interval At. To do this, at the end of the measured interval, shaper 1 generates a short pulse (Fig. 2e), which sets trigger 3 to one (Fig. 2e). Trigger 3 returns to its initial state with the last pulse from the output of delay element Yu (Fig. 2d). Thus, at the output of the trigger 3, a pulse of duration D- is formed, which flows through the element OR 4 to the inputs of two parallel-connected delay elements 8 and 9. The delay elements 8 and 9 are selected on the basis of the following conditions, T.

T T

T - Tj & T, where T is the time delay created by the delay element 8; T, is the time delay, created by the delay element 9; DT is a value that determines the measurement discreteness, is selected based on the permissible measurement error. 0 The inputs of the element And 12 receive impulse signals of duration At, but shifted one relative to the other by time 4.T (Fig. H, h). At the output of the element 12, an S pulse of duration is generated, which is fed to the counting input of the low-order bits of the reversing counter 13, the counters 13 and 14 operate in the subtraction mode, since the input

the signal (ended. The output pulse of the AND 12 element also arrives at the second input of the element OR 4. Next, the pulse circulation process in a closed loop (elements 4, 8, 9, 12) proceeds in a similar way, and in each cycle the circulation pulse duration is reduced by ( Fig. 2, k, l, m, i.) Circulation will occur when the duration of the inversion pulse T becomes less than the LT value. At the end of the circulation process, a code proportional to the interval being measured will be recorded in counters 13 and 14

.

where N is the number of cycles of inversion in the contour of elements 4, .8, 9, 12. To ensure uniformity of the overall reference scale, i.e. docking scales exact (younger bits reversible counter 13) and a rough count (older discharge counter reversal 14), the value must be a multiple of the base degree of the adopted numbering system.

Thus, the proposed device can be performed completely on digital microcircuits without using elements of analog technology. This circumstance will significantly reduce the cost of tuning the converter and increase the reliability of the device. Improving the metrological characteristics of the proposed converter (as opposed to the known devices) does not entail any additional costs, since this is achieved by reducing the delay time difference DT, created by delay elements 8 and 9. When used as delay elements of the radio frequency, cable ( and this is the most commonly used method for creating a precision delay, increasing accuracy by decreasing the sampling rate & T is accomplished by shortening the geometric length of the cable in delay element 8, which does not incur additional costs.

Claims (2)

1. USSR author's certificate 264229, cl. G 10 F 10/00, 1968. 2. Authors certificate of the USSR 506827, cl. G 04 F 10/04, 1975. . 1